Oil is commonly cleaned in an oil cleaning system which can receive cleaning water. The cleaning water can remove contaminants (e.g., salts) from the oil until, for example, the oil reaches a specified cleanliness level. The water exiting the oil cleaning system can include, for example, residuals of the oil. In order to be recycled, typically, a maximum amount of oil in the water (e.g., an amount in parts per million) can be specified (e.g., by a municipality, town, etc.) as an indicator of whether the water is recyclable or not.